Chisels are often used to divide a substrate into a plurality of fragments. To do this, the user places the chisel against the substrate. The chisel first penetrates the substrate along its axis. The chisel forces out material by producing compressive stresses. When these stresses exceed the resilience of the substrate, the latter breaks up around the chisel. However, when the substrate is able to withstand the stresses, the chisel can become stuck in the substrate. When this occurs, great physical effort may be required to remove pull the chisel out of the substrate.